Johnny G Pipe

Its funny how you buy something, think its PERFECT, and then the little desires for improvement creep in... I have developed a problem with the well known slight natural nose-high attitude of these cars, but am reluctant to mess about too much with the stock set up. I am aware that some folks opened a pandoras box when they went lower. I am considering replacing front springs only, with the generic 'TuV approved' 30mm lowering springs -of the sort type 911 etc sell. I really want to close up that gap, and I suspect the rear set up is a bit tired and already lower than when new anyway.

Anyone done this, or know if it would adversely affect handling? I am aware of the increased risk of hitting the bump stops and slightly harsher ride, but is a mismatch between front and rear spring types important/dangerous?
If only someone would re-manufacture the dopke lowering perches...
BTW I am also going to be eventually fitting some used 17" turbo twists - have bought them but still on relatively new tires on the d90's.
Thanks for help.

joey bagadonuts

I think the short answer is, no, it's probably not a good idea.

For starters, who manufactures the replacement parts? Unless it's Eibach or H&R, you're probably buying items not specifically designed for our cars. These companies spend a great deal of time developing products for specific cars. What do you know about the "generic" items? Unfortunately, neither company offers these items in pairs so you'll probably need to buy the full set.

Second, the stock springs are linear, while the H&R and Eibach items are progressive, i.e. the spring rates change with the amount of compression. To find linear springs with the appropriate rates and length would probably require some serious hunting on your part.

Finally, the switch to a lowering spring may actually produce a LESS harsh ride. I can only speak to the Eibach Pro-Kit installed on my car, but the harshness up front has been noticeably reduced. Perhaps someone can comment on the H&R. As for the ride at rear, the Eibachs also reduced the squat which is quite noticeable under hard acceleration with stock springs. It's firm, but again, not harsh.

And, of course, I'd recommend you swap out the shocks at this time to save yourself excessive labor expense. It's an 8-10 hour job for installation, corner balance and alignment. Sorry, but that's really the best approach, IMHO.
<img src="graemlins/beerchug.gif" border="0" alt="[cheers]" />

Jeff Curtis

I'm with Joey B. - NO!

If anything, you want stiffer springs in the rear! Most springs you purchase are going to be progressive rate springs anyway, unless you get the straight coil Eibach springs...and MOST factory applications are NOT progressive.

Get yourself a set of H&R 964 sport/lowering springs and some Bilstein HD (no "sport" version available, per say) and have a blast.

You won't stiffen up your car too much, not much of an improvement over M030 suspension anyway...that's why I installed 965 Turbo H&R sport/lowering springs.

If you get new springs and use your original BOGE shocks, you run the risk of spending a lot on labor and finding out that your Boge shock originals were just about kaput anyway.

This is something you only want to invest in once...right JohnFM?

Bill Gregory

[quote]<strong> and MOST factory applications are NOT progressive. </strong><hr></blockquote>

Well, depends. 964 Carrera RS, RSR, and Cup cars used progressive springs - either one progressive spring per wheel or main spring and helper spring per wheel.

That said, I agree with Joey and Jeff. Stay with a matched set of springs front and rear. When you replace the stock springs with lowering springs, suggest corner balancing, in addition to alignment, to ensure the best handling.

You know when you go to 17's that you need to change the 2 steering stops from the 6mm one's you have now to the 10mm ones that were installed from 1992 on, to support 17" tires.

FlyYellow

I agree - replacing just the front springs sounds like a bad idea. Then I asked myself - WHY is it a bad idea?

Here is my theory - I'd appreciate any commentatry. I'm thinking in an ideal handling situation, you corner the balance the car to get the right height & weight on all four corners. I would imagine that lowering the front only would cause a substantial shift in the geometery of the car, resulting in a lower center of gravity in the front vs. the rear.

Next question. What's wrong with that? I guess as you experience hard cornering the lower center of gravity in the front would tend to shift more weight to the front, thereby plating it more and making the tail even more likely to break loose.

In acceleration/decceleration the car would be changing the way it shifts weight, but I can't imagine a big problem with that.

So any thoughts here - am I way off base?

Cheers,
Boris

Christer

Johnny

Even different makes of tyres front/rear make a huge difference to handling, let alone modifying the front suspension components on their own. You might get lucky, but I wouldn't recommend it. Save up for the springs and shocks to be replaced together, your shocks are probably knackered anyway. Learn from JohnFM's experience.

Johnny G Pipe

Yep, thanks guys. I suspected it was wishful thinking. I really can't fault the car's general handling on public roads, so I'll wait and see how that gap looks with the 17's.
Maybe I'll put a couple of bags of potatoes in the front as a cheap way to gain that slammed RS look in the meantime........

PS Bill, thanks for advice: The wheels' vendor sent me a copy of the Porsche tech bulletin detailing the changes needed.

joey bagadonuts

More bad news. The 17's will probably make it look worse.

Here's the thinking. First, you need to remember that changing wheel diameters does not change the overall diameter of the tire being used. That number stays at ~25". To maintain a constant OD when switching to larger wheels, the tires' sidewall height is reduced. This number is commonly referred to as the aspect ratio. Now, with the lower profile rubber, the size of the gap relative to the sidewall has increased and gives the appearance of a larger gap even though that dimension did not change.

I believe the <a href="http://www.tirerack.com/index.jsp" target="_blank">Tire Rack</a> website has loads of information regarding tires, "plus sizing", understanding tire specs and the visual effects of lowering.

SympathyForTheDevil

Er... Johnny, if I were you, I'd rather wait to put the 17" rims on.
I believe that if you change only this item without doing a complete spring/damper job/upgrade, you are looking for BIG TROUBLE...
What you seek is to improve the handling of your car, right ?

So if you want to enjoy it, take the complete setup, or keep it stock and well maintained...

MelissaM

I'll chime in here.

I had a set of H&R springs put on my car while I still had the original 16" wheels. The difference it made in handling was tremendous! Little body roll, and the car felt like it could take on any corner at any speed.

The H&R's are progressive springs, so the ride is not harsh. (Probably similar to the Eibachs.)

The H&R's lowered my car about 1.5" -- took care of the fender gap in the front.

About a year after doing the springs, I put a set of 17" Boxster wheels on -- they fit just fine. Of course, YMMV.

Hope this helps!

-- Melissa

Johnny G Pipe

All replies appreciated. I'm sorry to get everyone talking about springs only vs springs and shocks..again!!
I have to admit that the main/only reason for lowering at this point is aesthetics. I think it is a fine handling car 'as is'. I just got it into my head that it looked a bit, well, tired at the rear, with lots of air between the front wheel and arch, like old Ford Capris always do. The recent thread featuring many lowered cars did nothing to help my roving eye!
I was looking for a relatively simple and non-meddling way to reduce that gap, and there doesn't appear to be one.
To be honest, after what I have read, I think I can live with it - and I'm not financially in a position to replace the whole suspension set-up just now.
On the other hand, Melissa'a experience, and Phil Raby's in the Porsche magazine make me think I'll consider springs allround - but maybe next year, after the 17's....
Thanks again!

Christer

[quote]Originally posted by SympathyForTheDevil:
[QB]Er... Johnny, if I were you, I'd rather wait to put the 17" rims on.
I believe that if you change only this item without doing a complete spring/damper job/upgrade, you are looking for BIG TROUBLE...
QB]<hr></blockquote>

Sympathy

Many of us have done the 17" wheel upgrades before doing any suspension upgrades. This is not a problem and improves the handling considerably. Make sure you do a full alignment though.

johnfm

YES - I think its a bad idea!

Not sure I know why, just a feeling I guess...... <img src="graemlins/c.gif" border="0" alt="[ouch]" /> <img src="graemlins/c.gif" border="0" alt="[ouch]" /> <img src="graemlins/c.gif" border="0" alt="[ouch]" />

Roygarth

[quote]Originally posted by joey bagadonuts:
[QB]More bad news. The 17's will probably make it look worse.

Here's the thinking. First, you need to remember that changing wheel diameters does not change the overall diameter of the tire being used. That number stays at ~25". To maintain a constant OD when switching to larger wheels, the tires' sidewall height is reduced. This number is commonly referred to as the aspect ratio. Now, with the lower profile rubber, the size of the gap relative to the sidewall has increased and gives the appearance of a larger gap even though that dimension did not change.

QB]<hr></blockquote>

Hi Joey

Interesting theory. But surely as the 'gap' and the 'tyre sidewall' are both black, the 'visual gap' is the 'gap + tyre side wall' ie the distance between wheel rim and the wheel arch. Therefore with a 17" wheel the 'gap' will appear smaller than with a 16" wheel?!

<img src="graemlins/sleep.gif" border="0" alt="[sleep]" />

BR
Piers

Christer

Piers and Joey

You are both correct. The bigger wheels gives the illusion that the gap(s) are smaller but in reality the diameter of the wheel/tyre combo will be the same (or therebaouts).